This invention relates to the stacking of materials, and, more particularly, to the stacking of relatively large volumes of material.
There are many situations where it is desirable to deal with large volumes of material. One example is in the operation of high speed processing machinery. Unless the materials to be processed are available in sufficient quantities, the machinery will not be able to operate at full capacity.
Another example is the movement of materials over long distances. It is apparent that the subsequent handling of the materials will be expedited if they are pre-stacked.
It is common practice to form stacks of materials on support structures such as pallets. The entire stack can then be moved by lifting the pallet.
Of course, if the materials are not arranged properly, the stack will not be able to provide the maximum quantity per unit volume. In addition, the stack may be unstable, particularly if it is large.
In order to provide stability and stack efficiency, it is common practice to form the stacks in tiers or layers, with each tier having a particular pattern. The patterns can then be alternated or varied in successive tiers in order to strengthen the average stack.
It is apparent that such a stack can be formed manually, but that is labor intensive. It is fatiguing to the stackers and relatively slow.
Numerous attempts have been made to reduce the fatigue factor and the number of persons needed for stacking. In various semi-automatic systems now in use, takes place by an operator at the top of an inclined conveyor to which the items to be stacked are fed.
In one such arrangement, the stacker machine makes use of an open top elevator. Initially the elevator platform is fully elevated. An operator receives items to be stacked at the top of an inclined feed conveyor and places them at the top opening in a desired pattern on the elevated platform to form a base tier. The elevator platform is then lowered by one tier level and a new tier is formed on the prior tier. This procedure is repeated until the entire stack is formed and the platform is in its base position. The completed stack is then removed from the machine and sent on its way.
While an improvement over purely manual stacking, the elevator stacker has a number of disadvantages. The movable platform has to support the full weight of the overall stack and therefore must be mechanically rugged and complex. More importantly, the operator is positioned at the top of the elevator. Not only is there limited space for movement, the operator must remain in position throughout the stacking operation. Consequently he is not available for ground level activities that are inevitably required. Finally, the items to be stacked must be transported to the top of the elevator by a relatively large inclined conveyor. The result is that a lot of space is need for the stacking operation.
In a variant of the elevator stacker, the platform is made to carry each tier to the appropriate stack level and return to the top of the elevator to receive a subsequent tier. While this arrangement allows the platform to operate with a reduced load, the principal disadvantages of the ordinary elevator stacker remain, namely the need for an operator at the top of the elevator, so that he is unavailable for ground level duties, and the need for a relatively long, inclined conveyor to carry the materials to the stacking position, so that a significant amount of equipment space is required.
Accordingly, it is an object of the invention to expedite the stacking of materials. A related object is to expedite the stacking of large volumes of material.
Another object of the invention is to enhance the effectiveness of stacking with mechanical equipment. A related objective is to enhance the effectiveness of stacking with semi-automatic equipment.
A further object of the invention is to achieve automated stacking using a limited amount of equipment space. A related object is to eliminate the need for relatively long, inclined power conveyors in semi-automatic stacking.
Yet another object of the invention is to enhance operator effectiveness in semi-automatic stacking. A related object is to make the operator in semi-automatic stacking available for other ground level duties, as well as the control of stacking. Another related object is to eliminate the need for stationing an operator at relatively high levels (as much as eight feet) above ground level in semi-automatic stacking.